Lightning arrester



Nov. 3, 1942. s. B. ROLOSON 2,300,846 LIGHTNING ARRESTER Fiied Sept. 20, 1939 r ix INVENTOR. flaw/520105011 A TTORNEYS.

Patented Nov. 3, 1942 rson'mma ABBESTEB Glenn B. Roloson,

Application September 3 Claims.

amended April The invention .described herein may be manufactured and used by or for theGovernment of the United States for governmental purposes without the payment to me of any royalty thereon in accordance with the provisions of the act of April 30, 1928" (ch. 460, 45St. L. 467).

My invention pertains to lightning arresters 'for the prevention of interruptions to service and damage to connected apparatus due to surges produced by lightning or other causes One of the earliest and simplest forms of protective devices for relieving electric transmission and distribution lines from excess voltage, produced by lightning or other causes, was to bring an electrode connected to the line in close proximity in open air to an electrode connected with the ground. These electrodes were spaced at such a distance apart that the normal line voltage was not sufilclent to start a current to flow between the electrodes. However. the electrodes were close enough to each other that. when an abnormal voltage appeared between the line and ground the current would discharge between the electrodes, thus reducing the excess voltage between line and ground.

One of the difiiculties of the above-described unconfined air gap was that "when an arc was once formedbetween the electrodes the normal line voltage was sufllcient to maintain an arc across the. electrodes, thus leaving a virtual ground on the line after the device had operated. This current flow across the electrodes, created by an excess voltage surge but main- Crestone, Colo. 1939, N0. 295,778

(Cl. 115-30) (Granted under the actor March 3, 1883, as

The external air gap is a complication which introducesextra hazards. offers more opportunity for birds toshort circuit the line and renders the lightning arrester less reliable due to the difiiculty of keeping the electrodes in the.

proper spacerelation. Also the energy of the arc in the external air gap is of very little benefit in interrupting the follow-up current, whereas, if the entire arc were to take place in a confined space, the energy of all the arc would be available to produce gas extinguish'the followup current.

A series oi air gaps is used rather than a single gap in some lightning arresters because multiple gaps are quicker in action that single gaps.

Also metallic rings have been used for inter mediate electrodes, but advantage has not been taken of these rings to direct the flow of. gas so as to. force the are against the sides of the gas-producing tube.

with the foregoing and other objects in view...

my invention resides in the combination of parts and in the details of construction hereinafter set forth in the following specification and appended claims, certain embodiments thereof having the characteristics of my invention and by which the same maybe practiced being illustrated in the accompanying drawing in whichtained by normal line voltage, is referred to as the follow up current." Various methods have been utilized to interrupt the follow up current, perhaps the most successful being patterned after i a common type of the expulsion fuse which has been in use for a considerable period of time. The arc between the electrodes in this fuse was enclosed in a fibre tube which was open at one.

order to overcome this difilculty, many'of these arresters use an external air gap in series with the tube.

Figure 1 is a perspective view of the assembled arrester;

Figure. 2, detailed views in elevation of the unassembled elements arranged successively in the order of assembly; and- I Figure 3, a vertical cross section through the assembled unit. I a

My invention comprises a suitable hollow or cored body having the insulating. or dielectric characteristics of porcelain, glass, etc., the bore or hollow of which is suitably, though not necessarily, elongated and of relatively small cross sectional area. In connection with this body which defines a chamber, I provide suitable electrode means for connecting a lead from a power line and a ground terminal into communication with the chamber at points removed from each other. The chamber or passageway between the line and ground connections is provided with a liner of suitable gas evolving material, and an intermediate electrode spaced with respect to the line and ground electrodes. electrode is provided with a somewhat smaller opening or path than that of the lined spark gaps between the intermediate electrode and the line and ground connections.

The intermediate electrode is further char- The intermediate the electrode.

acterized by an. opening which flares at the mouths thereof to an opening substantially that of the aforesaid spark gap chamber so as to facilitate the flow of gas through the somewhat smaller passageway of the electrode. Gas. passing through the electrode is thus caused to flow along the axis of the air gap and in doing so forces arcs within the spark gaps against the gasevolving liner. If the arc is permitted to flow along the axis, of the air gap rather than effectively close to the liner. the rate at which gas will be caused to evolve from the liner may be inadequate to completely nonionize the path and thus fail to destroy the arc.

The voltage of the line upon which the device is intended to be used is a determinative factor for the diameter, length and area of the spark gaps. The present invention renders external gaps unnecessary. Therefore, the spacing of'the intermediate electrode with respect to the line and ground connections should be considerably less than the space between the line and ground connections to insure the passage of arcs through the .device rather than across the terminals outside of the insulator body.

By reference to an embodiment, exemplifying the application of my invention, illustrated in the accompanying drawing it.will be seen as comprising an expulsion tube type of arrester. The. bore ll! of the insulator body II is provided. at the mouths thereof, with suitably secured hollow electrodes l2 and I3. As a suitable method of securing a lead from a power line ll to the terminal electrode l2, a stud i5 is threaded into This stud may in turn be provided with suitable securing means. such as a pair of nuts l6 and I1, between which the lead may be clamped as shown. In order that the passageway of the ground connecting electrode l3 remain unobstructed for the free expulsion of gases, the ground terminal may be. secured to the outer walls of the electrode. This may be satisfactorily accomplished by the utilization of a mounting bracket l8 provided with a hole through which a protruding end of the electrode may ex tend and upon which extending end a securing nut l9 may be applied. The ground terminal may be suitably secured to the mounting bracket or clamped to the electrode by the nut l3.

Within the bore ill of the insulator body and spaced from the respective terminal electrodes l2 and I3 there is mounted a liner 20 of suitable material. of minimum conductivity, yet gasevolving, of the type conventionally used in the art of the class to which this invention pertains. This liner lines a portion of the walls of the bore I and provides a centrally disposed unobstructed arc path 2|. to be positioned in an upright manner and though the stud l will ordinarily close the bore [0 to the entrance of water, and though the liner is pref-.

erably of nonconductive material, it is spaced from the respective terminal electrodes to prevent its serving as a current conductor from one electrode to the other. In the alternative, if it is preferable to have the liner in contact with the terminal electrodes it may be provided with a separation elsewhere to prevent a bridging over from one electrode to the other. The liner may be retained in spacd position by any suitable means, one of which is shown in the drawing as comprising a shoulder 22 within the bore l0 upon which the liner is brought to rest.

Within ends of the liner is positioned an Though the device is ordinarilv smaller passageway 24 than that of the lined path 2|, though preferably coaxial or in axial alignment therewith. It will be noted, however,

that the mouths 25 and 2i of the intermediate electrode pasageway 24 flare to substantiallythe size of the passageway 2| for the performance ,of the unique functions set forth elsewhere in this specification.

Suitable means or arrangements may be pro- .vided or made for maintaining theposition of the intermediate electrode 23. For example, the overall diameter or cross sectional area of the electrode may be substantially that of the bore l0 of the insulator body II and project through and rest upon the penetrated surface of the liner 20. A suitable arrangement is shown in the illustrated embodiment wherein it will be seen that the electrode is provided with a circumscribing annular flange 21 which extends through a separation in the liner 2!! and may either rest thereon or extend intoirictional contact with the walls of the bore "I. By such an arrangement of the flange 21 it will be seen that the length of the spark gap between the intermediate electrode and either terminal electrode is shorter within the lined pasageway than the space between the flange 21 and either terminal electrode.- It follows, therefore, that an arc is more apt to flow within the lined passageway than between the liner and the wall of the bore 10. The liner may be spaced from the intermediate electrode rather than from the terminal electrodes but by the use of an intermediate electrode of the character just described it is believed more desirable to space A plurality of intermediate electrodes 23 and 23 may be provided, as shown in theembodiment'illustrated, to insure the destruction of an intermediate electrode 23 having a somewhat are ln'the event that the air of the spark gap fore and aft of the first intermediate electrode 23-is not sufficiently non-ionized or deprived of its conductivity by gas from the liner to extinguish the arc. It is also known that an arc will flash over a series of short spark gaps sooner than over a single gap of a length substantially the same as the sum of the length of the series of short gaps.

From the foregoing description and the illustrated embodiment it will be seen that the construction .of the intermediate "electrode is such as to direct theexpulsion gases along the axis of the passageway and thereby force electric arcs against or close to the fibre liner whereby the heat of the arcs will be more effective upon the liner to produce a greater volume of nonionized gas. The non-ionized gas flrst of all destroys conductivity and second the downward force of the gas tothe exit l3 tends to extinguish the arcs. Except for an opening in the bottom of the device, the operative elements are completely shielded from weather and-foreign .objects which may. destroy their effectiveness.

tional lightning arresters and fibre tubes of conventional expulsion tubes are usually considered non-conductive and insulating, the known fact remains that they are more or less conductive and subject to charring, deterioration and destruction by reason of the contact of this material with terminal electrodes having a difference of potential constantly impressed across them. The prevention of any current flow, from one terminal electrode to the other, through the liner also precludes the possibility of radio interference.

It will also be seen that the device herein described provides for an unobstructed exit for the gas to prevent the building up of pressure sufficient to burst the device.

Having thus described my invention what I claim is:

1. A vented electric discharge device of the expulsion tube type comprising a pair of terminal electrodes, an insulator body having the insulating characteristics of porcelain or glass and having a passageway therethrough into which said electrodes extend in spaced relation, said body being the sole structure completely bridging the space between saidelectrodes, the inwardly extending ends of said electrodes presenting annuiarly arranged opposed surfaces substantially coaxial with said passageway and providing a plurality of substantially uniform arc discharge paths wholly within said passageway and between the various points on the respective annular surfaces of said electrodes,

7 means between said electrodes comprising gas evolving material having an open passageway therethrough substantially coaxial with said body passageway and with surfaces of said material on planes substantially coincident with said are paths where arcs will have their greatest heat effect on said material for the production of gases, and said device having between said electrodes, in addition to said means, a gap structurally bridged only by said insulator body having less current conductive characteristics than said gas evolving material and of alength adequate to stand normal line voltage without discharge thereacross, whereby said gas evolving material is out of electrical circuit with said terminal electrodes and current leakage through said gas evolving material under normal line voltage is blocked.

2. A vented electric discharge device of the expulsion tube type comprising a pair of terminal electrodes, an insulator body having the insulating characteristics of porcelain or glass and having a passageway therethrough into which said electrodes extend in spaced relation, the inwardly extending ends of said electrodes presenting annuiarly arranged opposed surfaces substantially coaxial with said passageway and providing a plurality of substantially uniform arc discharge paths wholly within. said passageway and between the various points on the respective annular surfaces of said electrodes, means be-.,

tween said electrodes comprising an auxiliary conducting body mounted, in spaced relation to said electrodes, said means also comprising gas evolving material having an open passageway therethrough substantially coaxial with said body passageway and with surfaces of said material on planes substantially coincident with said are paths where arcs will have their greatest heat quate to stand normal line voltage without discharge thereacross, whereby current leakage through said gas evolving material under normal line voltage is blocked.

3. A vented electric discharge device of the I expulsion tube type comprising a pair of termileakage through said gas evolving material under.

nal electrodes, an insulator body-having the insulating characteristics of porcelain or glass and having a passageway therethrough into which said terminal electrodes extend in spaced relation, the inwardly extending ends of said terminal electrodes presenting annuiarly arranged opposed surfaces substantially coaxial with said passageway andproviding a plurality of substantially uniform arc discharge paths wholly within said passageway and between the various points on the respective annular surfaces of said terminal electrodes, tubular gas eyo'lying material between said terminal electrodes'l-having an inner cross sectional area substantially that of the annular surface of one of said electrodes and mounted within said passageway intermediate of and substantially coaxial with said electrodes and with inner surfaces thereof on planes substantially coincident with said are paths where arcs will have their greatest heat effect on said material for the production of gases, an auxiliary conducting body mounted between said electrodes, said auxiliar body having an orifice therethrough-substantially coaxial with said passageway and of smaller cross-sectional area than the inner cross sectional area of said tubular gas evolving material whereby gasesflowing through said auxiliary conducting body are directed-axially of said passageway, said gas evolving material and auxiliary body being out of electrical contact with said terminal electrodes to provide a gap therebetween' which is structurally bridged only by said insulator whereby current normal line voltage is blocked.

' GLENN B. Romson. 

